Multi-layered aluminium brazing sheet material

ABSTRACT

Multilayered brazing sheet material including an aluminum core alloy layer having a first brazing clad layer material on one face of the core layer and a second brazing clad layer material on the other face of the core material, and an inter-layer between the core layer and the first brazing clad layer material, wherein the core layer is 3xxx-series aluminum alloy having, in wt. %, up to 0.4% Si, up to 0.5% Fe, 0.4% to 0.75% Cu, 0.6% to 1.1% Mn, up to 0.04% Mg, up to 0.2% Cr, up to 0.25% Zr, up to 0.2% Ti, up to 0.15% Zn, balance aluminum and impurities, wherein the first brazing layer and the second brazing layer are 4xxx-series aluminum alloy having 7% to 14% Si and up to 2% Mg, balance aluminum and impurities, and wherein the inter-layer is aluminum alloy of the 1xxx-series alloys.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a § 371 National Stage Application of International ApplicationNo. PCT/EP2015/063694 filed on Jun. 18, 2015, claiming the priority ofEuropean Patent Application No. 14179088.1 filed on Jul. 30, 2014.

FIELD OF THE INVENTION

The invention relates to a multi-layered brazing sheet materialconsisting of an aluminium core alloy layer provided with a firstbrazing clad layer material on one face of said aluminium core layer anda second brazing clad layer material on the other face of said aluminiumcore material, and an interlayer or inter-liner positioned between thealuminium core alloy layer and the first or second brazing clad layermaterial. The invention further relates to a brazed heat exchangercomprising various components and at least one component being made fromthe aluminium alloy brazing sheet according to this invention.

BACKGROUND TO THE INVENTION

As will be appreciated herein below, except as otherwise indicated,aluminium alloy designations and temper designations refer to theAluminum Association designations in Aluminum Standards and Data and theRegistration Records, as published by the Aluminum Association in 2014.

For any description of alloy compositions or preferred alloycompositions, all references to percentages are by weight percent unlessotherwise indicated.

Substrates of aluminium or aluminium alloy in the form of sheet orextrusion, are used to make shaped or formed products. In some of theseprocesses parts of (shaped) aluminium comprising substrates areinterconnected. One end of a substrate may be interconnected with theother end or one substrate may be assembled with one or more othersubstrates. This is commonly done by brazing, a technique well known tothe person skilled in the art. In a brazing process, a brazing fillermetal or brazing alloy, or a composition producing a brazing alloy uponheating, is applied to at least one portion of the substrate to bebrazed. After the substrate parts are assembled, they are heated untilthe brazing metal or brazing alloy melts. The melting point of thebrazing material is lower than the melting point of the aluminiumsubstrate or aluminium core sheet.

Brazing sheet products find wide applications in heat exchangers andother similar equipment. Conventional brazing products have a core ofrolled sheet, typically, but not exclusively an aluminium alloy of the3xxx-series, having on at least one surface of the core sheet analuminium clad layer (also known as an aluminium cladding layer). Thealuminium clad layer is made of a 4xxx-series alloy comprising siliconin an amount in the range of 2% to 20% by weight, and preferably in therange of about 6% to 14% by weight. The aluminium clad layer may becoupled or bonded to the core alloy in various ways known in the art,for example by means of roll bonding, cladding spray-forming orsemi-continuous or continuous casting processes. These aluminium cladlayers have a liquidus temperature typically in the range of about 540°C. to 615° C.

There is a need for further improved brazing sheet materials that can besupplied in a fully annealed temper, and is sufficiently formable toproduce complex shaped aluminium substrates, and that can be exposed toboth vacuum brazing and controlled-atmosphere brazing (“CAB”) events,and achieves high levels of post-braze corrosion resistance.

DESCRIPTION OF THE INVENTION

It is an object of the invention to provide a brazing sheet materialthat meet this need, or at least an alternative product capable of beingsupplied in a fully annealed temper, and is sufficiently formable toproduce complex shaped aluminium substrates, and that can be exposed toboth vacuum brazing and controlled atmosphere brazing events, andachieves high levels of post-braze corrosion resistance.

This and other objects and further advantages are met or exceeded by thepresent invention providing a 4-layered brazing sheet materialconsisting of an aluminium core alloy layer provided with a firstbrazing clad layer material on one face of said aluminium core layer anda second brazing clad layer material on the other face of said aluminiumcore material, and an inter-layer positioned between the aluminium corealloy layer and the first brazing clad layer material, wherein the corelayer is made from an 3xxx-series aluminium alloy having, in wt. %, upto 0.4% Si, up to 0.5% Fe, 0.4% to 0.75% Cu, 0.6% to 1.1% Mn, up to0.04% Mg, up to 0.2% Cr, up to 0.25% Zr, up to 0.2% Ti, up to 0.15% Zn,balance aluminium and impurities, wherein the first brazing layer andthe second brazing layer are made from an 4xxx-series aluminium alloyhaving 6% to 14% Si and up to 2% Mg, balance aluminium and impurities,and wherein the inter-layer is made from an aluminium alloy of the1xxx-series alloys.

The brazing sheet material according to this invention has a very goodcorrosion resistance in acidic environments, can be subjected to cyclictemperature and pressure variations, as typically found in automotiveapplications (e.g. as the result of spent fuel vapour condensation), andas such, the brazing sheet material is suitable for being applied indirect air-to-air charge air cooling (“CAC”) or intercooling,air-to-water CAC, water-to-air CAC, exhaust gas cooling, exhaust gasrecirculation systems, hybrid cooling system, two-phase cooling systems,etc., and forms at least an alternative product capable of extending theserviceable life of such heat exchanger units beyond the scope ofperformance feasible with the current art. The brazing sheet material isproducible as coil and sheet, to support mass production scale and batchscale processing, and is sufficiently formable to produce the complexshaped aluminium substrates referenced above. The brazing sheet materialis of sufficiently high quality to allow repeatable brazing andconsistent component performance. The brazing sheet material isbrazeable in both controlled atmosphere brazing process, either with orwithout the application of a brazing flux material, and vacuum brazingprocesses and has high thermal stability in CAC cyclic operation. Inaddition the brazing sheet material achieves high levels of post-brazeinternal cleanliness.

In an embodiment the 3xxx-series aluminium core alloy is made from analuminium alloy consisting of, in wt. %:

-   -   up to 0.3% Si, and more preferably up to 0.2%,    -   up to 0.5% Fe, preferably in a range of 0.15% to 0.45%, and more        preferably 0.25% to 0.45%,    -   0.4% to 0.75% Cu, preferably 0.50% to 0.70%, and more preferably        0.50% to 0.68%,    -   0.6% to 1.1% Mn, preferably 0.7% to 1.0%, and more preferably        0.7% to 0.95%,    -   up to 0.04% Mg, preferably up to 0.02%, such that the aluminium        alloy is substantially free from Mg,    -   up to 0.2% Cr, preferably up to 0.09%, more preferably up to        0.04%,    -   up to 0.25% Zr, preferably up to 0.09%, more preferably up to        0.04%,    -   up to 0.2% Ti, preferably 0.05% to 0.2%, more preferably 0.06%        to 0.12%,    -   up to 0.15% Zn, preferably up to 0.1%,    -   balance aluminium and impurities.

The first and the second brazing clad liner are each made from a4xxx-series aluminium alloy having 6% to 14% Si and up to 0.35% Mg,ideally for use in a CAB process. Preferably the Si is up to 11%. The Mglevel is preferably up to 0.10%, and more preferably up to 0.04%, suchthat the aluminium alloy is substantially free from Mg. The balance ismade by aluminium and unavoidable impurities, which in practical termswould mean up to 0.6% Fe, up to 0.1% Mn, up to 0.08% Cu, up to 0.20% Zn,others each <0.05%, total <0.2%, remainder aluminium.

In an alternative embodiment the first brazing clad liner and the secondbrazing clad liner are each made from a 4xxx-series aluminium alloyhaving 6% to 14% Si and up to 2% Mg, balance aluminium and impurities.Preferably the Si content is in a range of 7% to 11% Si. Preferably theMg content is in a range of 0.4% to 2%, and more preferably 1% to 1.8%Mg, to enable the brazing sheet material to be used in a vacuum brazingprocess. The balance is made by aluminium and unavoidable impurities,which in practical terms would mean up to 0.6% Fe, up to 0.1% Mn, up to0.1% Cu, up to 0.2% Zn, others each <0.05%, total <0.2%, remainderaluminium.

In an alternative embodiment the first and the second brazing clad linerare each made from a 4xxx-series aluminium alloy having 6% to 14% Si, upto 0.5% Mg, up to 0.5% Bi and/or up to 0.5% Y, ideally for use in afluxless controlled atmosphere brazing process. Preferably the Si is upto 9%. The balance is made by aluminium and unavoidable impurities,which in practical terms would mean up to 0.6% Fe, up to 0.1% Mn, up to0.08% Cu, up to 0.20% Zn, others each <0.05%, total <0.2%, remainderaluminium.

The interlayer or inter-liner is made from an aluminium alloy of the1xxx-series alloys, preferably aluminium from the AA1050-series. The1xxx-series alloy has preferably a Zn-content of less than 0.1%, andpreferably of less than 0.05%. The AA1050-series alloy has by definitionof the Aluminium Association a Zn-content of less than 0.05%. In apreferred embodiment the interlayer has a thickness of 60 μm or less,for example of about 40 μm or about 50 μm, and is to control thediffusion of alloying elements, e.g. Si, from the core layer to thebrazing layer, and as such limits inter-granular corrosion propagationthrough the core layer in the post-braze condition, and therebysignificantly improve the post-braze corrosion performance of thebrazing sheet product when applied in a heat exchanger, in particular aCAC. The 1xxx-series interlayer also provides galvanic protection to the3xxx-series aluminium core alloy.

The brazing sheet material according to this invention can bemanufactured via various techniques. For example by roll bonding as iswell known in the art. Alternatively one or more of the layers can beapplied on the core alloy layer by means of thermal spraying techniques.Or alternatively the core alloy layer and the second brazing clad layercan be manufactured by means of casting techniques, for example asdisclosed in international patent document WO-2004/112992-A2 (Alcan) aspublished on 29 Dec. 2004, whereby further layers can be applied bymeans of for example roll bonding or thermal spraying techniques.

The brazing sheet material according to the invention has a typicalthickness at final gauge in the range of about 0.1 mm to 1.2 mm. Thebrazing sheet material is preferably up to about 1 mm thick at finalgauge, and more preferably up to about 0.6 mm.

Each of the first and second brazing layers has typically a thickness of5% to 15% of the total thickness, for example each of about 10%.

In an embodiment of the invention the core layer has been homogenisedduring its manufacturing route prior to hot deformation into thinnergauge material. Typically such a homogenisation heat treatment isperformed in a temperature range of 400° C. to 650° C. for a soakingtime in a range of 5 to 48 hours, to enable O-temper material.

In a preferred embodiment of the invention the brazing sheet material isprovided in an O-temper, and which is fully annealed.

In another embodiment of the invention the brazing sheet material isprovided in an H2x-temper, wherein x is 1, 2, 3, 4, 5, or 6. Morepreferably it is provided in an H24-temper.

In another aspect of the invention is relates to a brazed tube made fromthe multi-layered brazing sheet material according to this inventionacting as a fluid passage channel in a heat exchanger apparatus.

In another aspect of the invention is relates to a brazed heat exchangercomprising at least one tube made from the multi-layered brazing sheetmaterial according to this invention. Ideally the heat exchanger is acharge-air-cooler (“CAC”), also known in the art as an intercooler. Morepreferably in a water-CAC, in the art also known as a liquid-CAC.

The brazing sheet material is suitable for being applied also inair-to-water CAC, water-to-air CAC, exhaust gas cooling, exhaust gasrecirculation systems, hybrid cooling system, and two-phase coolingsystems.

The invention claimed is:
 1. A multi-layered brazing sheet materialconsisting of an aluminium core alloy layer provided with a firstbrazing clad layer material on one face of said aluminium core alloylayer and a second brazing clad layer material on another face of saidaluminium core alloy layer, and an inter-layer positioned between thealuminium core alloy layer and the first brazing clad layer material,wherein the aluminium core alloy layer is made from a 3xxx-seriesaluminium alloy having, in wt. %, up to 0.4% Si, up to 0.5% Fe, 0.4% to0.75% Cu, 0.6% to 1.0% Mn, up to 0.04% Mg, up to 0.2% Cr, up to 0.25%Zr, up to 0.2% Ti, and up to 0.15% Zn, balance aluminium and impurities,wherein the first brazing clad layer material and the second brazingclad layer material are made from a 4xxx-series aluminium alloy having6% to 14% Si, up to 2% Mg, and up to 0.20% Zn, balance aluminium andimpurities, and wherein the inter-layer is made from an aluminium alloyof the 1xxx-series alloys having a Zn content of less than 0.1%.
 2. Thebrazing sheet material according to claim 1, wherein the aluminium corealloy layer is made from an aluminium alloy consisting of, in wt. %, upto 0.2% Si, 0.15% to 0.45% Fe, 0.50 to 0.7% Cu, 0.7% to 1.0% Mn, up to0.02% Mg, up to 0.09% Cr, up to 0.09% Zr, 0.05% to 0.2% Ti, and up to0.15% Zn, balance aluminium and impurities.
 3. The brazing sheetmaterial according to claim 1, wherein the aluminium core alloy layer ismade from an aluminium alloy consisting of, in wt. %, up to 0.2% Si,0.25% to 0.45% Fe, 0.50% to 0.68% Cu, 0.7% to 0.95% Mn, up to 0.02% Mg,up to 0.04% Cr, up to 0.04% Zr, 0.06% to 0.12% Ti, and up to 0.15% Zn,balance aluminium and impurities.
 4. The brazing sheet materialaccording to claim 1, wherein the first brazing clad layer material ismade from a 4xxx-series aluminium alloy having 6% to 11% Si and up to0.35% Mg.
 5. The brazing sheet material according to claim 1, whereinthe inter-layer has a thickness of 60 μm or less.
 6. The brazing sheetmaterial according to claim 1, wherein the inter-layer is made from analuminium alloy of the 1xxx-series alloys having a Zn-content of lessthan 0.05%.
 7. The brazing sheet material according to claim 1, whereinthe brazing sheet material has a total thickness of 0.1 to 1.2 mm. 8.The brazing sheet material according to claim 7, wherein each of thefirst and second brazing clad layer materials has a thickness of 5% to15% of the total thickness.
 9. The brazing sheet material according toclaim 1, wherein the aluminium core alloy layer has been homogenised.10. The brazing sheet material according to claim 1, wherein the brazingsheet material is provided in an O-temper.
 11. A brazing tube made fromthe multi-layered brazing sheet material according to claim
 1. 12. Aheat exchanger comprising a brazed tube made from the multi-layeredbrazing sheet material according to claim
 1. 13. A charge-air-coolerincorporating a brazed tube made from the multi-layered brazing sheetmaterial according to claim
 1. 14. A water charge-air-coolerincorporating a brazed tube made from the multi-layered brazing sheetmaterial according to claim
 1. 15. The brazing sheet material accordingto claim 1, wherein the first brazing clad layer material and the secondbrazing clad layer material are each made from a 4xxx-series aluminiumalloy having 6% to 11% Si and up to 0.35% Mg, balance impurities andaluminium.
 16. The brazing sheet material according to claim 1, whereinthe first brazing clad layer material and the second brazing clad layermaterial are each made from a 4xxx-series aluminium alloy having 6% to11% Si and up to 0.10% Mg, balance impurities and aluminium.
 17. Thebrazing sheet material according to claim 1, wherein the first brazingclad layer material is made from a 4xxx-series aluminium alloy having 6%to 11% Si and up to 0.10% Mg, balance impurities and aluminium.
 18. Thebrazing sheet material according to claim 1, wherein the aluminium corealloy layer has a Fe content of 0.25-0.45% Fe.
 19. The brazing sheetmaterial according to claim 1, wherein the aluminium core alloy layerhas a Mn content of 0.6% to 0.95%.
 20. The brazing sheet materialaccording to claim 1, wherein the Zn of the first brazing clad layermaterial and the second brazing clad layer material if present is not apurposefully added impurity.